Two Argentine police officers have been arrested and 100 more suspended after two protesters were shot dead during a wave of violent demonstrations observers say threaten the survival of the caretaker administration of President Eduardo Duhalde.

The action, in a country where crimes by the police often go unpunished, was prompted by the publication yesterday of photographs in the Buenos Aires press clearly showing police involvement in the incident.

The police had claimed that the shooting was the work of "infiltrators" among the demonstrators.

"Those in charge of maintaining order are the ones who carried out this atrocious manhunt," President Duhalde said yesterday after 14,000 people marched on the presidential palace demanding his resignation and protesting against the killing.

The shootings took place on Wednesday in the industrial Buenos Aires suburb of Avellaneda, during the worst outbreak of violence Argentina has seen since Mr Duhalde took office in January.

About 1,000 government demonstrators tried to cut off the main road into Buenos Aires and about 90 people were injured, many of them fired on while attempting to help others who had already been shot.

Protesters claimed that they were shot at indiscriminately by the police from rooftops and an elevated pedestrian walkway.

The protest was aimed at IMF-imposed austerity measures which many blame for a four-year-old recession that has plunged half of Argentina below the poverty line, causing alarming increases in malnutrition and infant mortality rates.

Following the country's default on its $141bn foreign debt in December, the Argentine peso has fallen 75% against the dollar and inflation is spiralling. In Buenos Aires, every day there are reports of children fainting at school because they have gone for days without eating - in a meat-exporting country that once prided itself as the "breadbasket of the world".

One of the two officers arrested for Wednesday's killings is Chief Inspector Alfredo Franchiotti, who was seen by witnesses inside Avellaneda railway station firing at a 21-year-old demonstrator, Dario Santillan, while Mr Santillan was trying to assist another man who had been shot just a few minutes earlier.

The man Mr Santillan was helping, Maximiliano Costeki, was dragged by fellow demonstrators into the station for cover. "Please help me, I'm burning," said Costeki before dying. "The cops shot me."

While Mr Santillan was kneeling over Costeki, witnesses say, the chief inspector burst in wielding an automatic rifle, heading a group of armed policemen. "Don't shoot," begged Mr Santillan as he got up to run away, only to be shot from behind by Mr Franchiotti, according to the witnesses.

They said Mr Santillan, bleeding copiously, was dragged outside the railway station by Mr Franchiotti's men and that the officer hurled insults at him.

Fearful of a repetition of the social upheaval that last December toppled the government of Fernando de la Rua and led to the quick-fire succession of five presidents in two weeks, Mr Duhalde's government has warned that there may be a plot to oust it.

There is "more than a suspicion" that the latest violence was not spontaneous, said cabinet chief Alfredo Atanasof.

The violence erupted as the Argentine economy minister, Roberto Lavagna, was leading desperate negotiations with the IMF in Washington for the reestablishment of its $18bn credit line, suspended in December.

Argentina is hoping that the new austerity measures it has imposed at the IMF's request will unlock badly needed loans that could be used to decompress the country's difficult social and economic situation.